Unlocked Phone

This is key. Buying local SIM cards is the cheapest way to get data wherever you are. Pop into the local Vodaphone or T Mobile store (or any number of other companies), pick up a SIM for $20 $30, and get a ton of (or even unlimited) data for a month if you have an unlocked phone. You need to do that part before you leave. Check with your provider to find out all the hoops you must jump through.